Efficiency of mixed and rigid occlusal stabilization splints: Randomized clinical trial

Abstract Occlusal stabilization splints are the most common treatment for controlling the deleterious effects of sleep bruxism. This study aimed to evaluate the effectiveness of a low-cost, mixed occlusal splint (MOS) compared to that of a rigid splint. A randomized clinical trial was performed on 43 adults of both sexes with possible sleep bruxism and satisfactory dental conditions. They were divided into rigid occlusal splint (ROS) (n = 23) and MOS (n = 20) groups. Masticatory muscle and temporomandibular joint (TMJ) pain intensity (visual analog scale), quality of life (WHOQOL-BREF), indentations in the oral mucosa, anxiety, and depression (HADS), number of days of splint use, and splint wear were evaluated. All variables were evaluated at baseline (T0), 6 months (T6), and 12 months (T12) after splint installation (T0), and splint wear was evaluated at T6 and T12. Student's t-test, Mann-Whitney U test, non-parametric Friedman's analysis of variance for paired samples and pairwise multiple comparisons, Pearson's chi-square test, two-proportion z-test, non-parametric McNemar's and Cochran's Q, and Wilcoxon tests were used (p < 0.05). In both groups, there was a decrease in TMJ pain and pain intensity over time and improvements in the quality of life scores. At T6, there was a higher rate of splint wear in the MOS group than in the ROS group (p = 0.023). The MOS showed a higher rate of wear than the rigid splint but had similar results for the other variables. Therefore, the use of a mixed splint appears to be effective in controlling the signs and symptoms of sleep bruxism.

Comportamiento Mecánico de un Premolar Humano Sano Sometido a Fuerzas Funcionales y Disfuncionales en un MEF / Mechanical Behavior of a Healthy Human Premolar Subjected to Functional and Dysfunctional Forces in a FEM

El propósito de este estudio fue analizar el comportamiento mecánico de la estructura dental sana de un primer premolar inferior humano sometido a fuerzas funcionales y disfuncionales en diferentes direcciones. Se buscó comprender, bajo las variables contempladas, las zonas de concentración de esfuerzos que conllevan al daño estructural de sus constituyentes y tejidos adyacentes. Se realizó el modelo 3D de la reconstrucción de un archivo TAC de un primer premolar inferior, que incluyó esmalte, dentina, ligamento periodontal y hueso alveolar considerando tres variables: dirección, magnitud y área de la fuerza aplicada. La dirección fue dirigida en tres vectores (vertical, tangencial y horizontal) bajo cuatro magnitudes, una funcional de 35 N y tres disfuncionales de 170, 310 y 445 N, aplicadas sobre un área de la cara oclusal y/o vestibular del premolar que involucró tres contactos estabilizadores (A, B y C) y dos paradores de cierre. Los resultados obtenidos explican el fenómeno de combinar tres vectores, cuatro magnitudes y un área de aplicación de la fuerza, donde los valores de esfuerzo efectivo equivalente Von Mises muestran valores máximos a partir de los 60 MPa. Los valores de tensión máximos se localizan, bajo la carga horizontal a 170 N y en el proceso masticatorio en la zona cervical, cuando la fuerza pasa del 60 %. Sobre la base de los hallazgos de este estudio, se puede concluir que la reacción de los tejidos a fuerzas funcionales y disfuncionales varía de acuerdo con la magnitud, dirección y área de aplicación de la fuerza. Los valores de tensión resultan ser más altos bajo la aplicación de fuerzas disfuncionales tanto en magnitud como en dirección, produciendo esfuerzos tensiles significativos para la estructura dental y periodontal cervical, mientras que, bajo las cargas funcionales aplicadas en cualquier dirección, no se generan esfuerzos lesivos. Esto supone el reconocimiento del poder de detrimento estructural del diente y periodonto frente al bruxismo céntrico y excéntrico.

SUMMARY: The purpose of this study was to analyze the mechanical behavior of the healthy dental structure of a human mandibular first premolar subjected to functional and dysfunctional forces in different directions. It was sought to understand, under the contemplated variables, the areas of stress concentration that lead to structural damage of its constituents and adjacent tissues. The 3D model of the reconstruction of a CT file of a lower first premolar was made, which included enamel, dentin, periodontal ligament and alveolar bone considering three variables: direction, magnitude and area of the applied force. The direction was directed in three vectors (vertical, tangential and horizontal) under four magnitudes, one functional of 35 N and three dysfunctional of 170, 310 and 445 N, applied to an area of the occlusal and/or buccal face of the premolar that involved three stabilizing contacts (A, B and C) and two closing stops. The results obtained explain the phenomenon of combining three vectors, four magnitudes and an area of force application, where the values of effective equivalent Von Mises stress show maximum values from 60 MPa. The maximum tension values are located under the horizontal load at 170 N and in the masticatory process in the cervical area, when the force exceeds 60%. Based on the findings of this study, it can be concluded that the reaction of tissues to functional and dysfunctional forces varies according to the magnitude, direction, and area of application of the force. The stress values turn out to be higher under the application of dysfunctional forces both in magnitude and in direction, producing significant tensile stresses for the dental and cervical periodontal structure, while under functional loads applied in any direction, no damaging stresses are generated. This supposes the recognition of the power of structural detriment of the tooth and periodontium against centric and eccentric bruxism.

Relationship between the occlusal plane and three different levels of ala-tragus line in a sample of sudanese adults / Relación entre el plano oclusal y tres niveles diferentes de la línea ala-trago en una muestra de adultos sudaneses

Aim: Correct orientation of the occlusal plane plays a vital role in achieving the perfect occlusal balance and function of complete dentures. This study aimed to evaluate the most reliable posterior reference point of the ala-tragus line (ATL) concerning occlusal plane (OP) in a sample of the dentate Sudanese population. Materials and Methods: A total of 150 subjects with healthy and well-aligned permanent teeth were randomly selected. Right lateral profile photographs were taken with subjects having a fox plane placed intra-orally, contacting the occlusal plane. Reference points corresponding to inferior, middle, and superior borders of the tragus and inferior border of the ala of the nose were marked on photographs. The angles between the lines were measured using the Auto-CAD software program, and the most parallel relationship was determined. Descriptive statistics in terms of means and standard deviations were presented. Independent t-test and one-way ANOVA tests were used to compare as appropriate. A p-value < 0.05 was considered significant. Results: The mean angle formed by the OP and ATL was 8.5±3.69º for the superior level, 4.68±3.13º for the middle line, and 2.89±2.57º for the inferior line. A significant difference was found between the means of the three angles (p< 0.001), while no significant difference (p> 0.05) was found between both genders regarding the measured angles. Conclusions: The line joining the inferior border of the ala of the nose with the inferior border of the tragus of the ear was the most reliable line in terms of parallelism to determine the occlusal plane orientation.

Antecedentes: La orientación correcta del plano oclusal juega un papel vital para lograr el equilibrio oclusal perfecto y la función de las prótesis completas. Este estudio tuvo como objetivo evaluar el punto de referencia posterior más confiable de la línea ala-trago (ATL) con respecto al plano oclusal (OP) en una muestra de la población dentada de Sudán. Materiales y Métodos: Se seleccionaron aleatoriamente un total de 150 sujetos con dientes permanentes sanos y bien alineados. Se tomaron fotografías de perfil lateral derecho de sujetos a los que se les colocó un plano de zorro intraoralmente, en contacto con el plano oclusal. En las fotografías se marcaron los puntos de referencia correspondientes a los bordes inferior, medio y superior del trago y al borde inferior del ala de la nariz. Los ángulos entre las líneas se midieron utilizando el programa de software Auto-CAD y se determinó la relación más paralela. Se presentaron estadísticas descriptivas en términos de medias y desviaciones estándar. Se utilizaron prueba-t independiente y prueba ANOVA unidireccional para las comparaciones, según correspondiera. Se consideró significativo un valor de p<0,05. Resultados: El ángulo medio formado por OP y ATL fue de 8,5±3,69º para el nivel superior, 4,68±3,13º para la línea media y 2,89±2,57º para la línea inferior. Se encontró una diferencia significativa entre las medias de los tres ángulos (p< 0,001), mientras que no se encontró diferencia significativa (p>0,05) entre ambos sexos con respecto a los ángulos medidos. Conclusión: La línea que une el borde inferior del ala de la nariz con el borde inferior del trago de la oreja fue la línea más confiable en términos de paralelismo para determinar la orientación del plano oclusal.

Oclusión basada en evidencia: rompiendo paradigmas / Occlusion based on evidence: breaking paradigms

La odontología basada en evidencias es una metodología que busca que las decisiones clínicas diarias que toman los profesionales en estomatología se encuentren fundamentadas en la evidencia científica, en ella se integran las experiencias clínicas, las necesidades, las preferencias del paciente y la evidencia clínicamente relevante más actual analizada por pares. Estos pilares son parte del proceso en la toma de decisiones para la atención al paciente. La odontología basada en evidencias surge de las exitosas experiencias obtenidas con el desarrollo e implementación de la medicina fundamentada en pruebas, al aplicar el método científico en la evaluación, planificación y toma de decisiones de las prestaciones sanitarias, sobre todo a través de los estudios controlados. En general, toda la práctica odontológica ha tenido grandes avances basados en evidencias, con hechos verídicos comprobados, pero los conceptos fundamentales de oclusión no han tenido una mejora cimentada en el conocimiento científico, prueba de ello es que se siguen ocupando teorías y conceptos de las filosofías de oclusión en la rehabilitación de muchos pacientes, seguimos creyendo en mitos y sofismas que no han podido ser demostrados. En esta revisión, demostramos los grandes avances en los conceptos de oclusión e invitamos a todos los odontólogos a romper los paradigmas de la oclusión antigua sin evidencias científicas y a utilizar las herramientas del método científico en la práctica clínica odontológica (AU)

Evidence-based dentistry is a strategy that seeks to ensure that the daily clinical decisions made by the dental professional are based on scientific evidence. It integrates the clinical experience of the dentist, the needs and preferences of the patient, and the most current relevant clinical evidence. All three are part of the decision-making process for patient care. Evidence-based dentistry arises from the successful experiences obtained with the development and implementation of evidence-based medicine, applying the scientific method in the evaluation, planning and decision-making of health benefits, especially through controlled studies. In general, all dental practice has had great advances based on evidence, with proven true facts, but the fundamental concepts of occlusion have not had an improvement based on scientific knowledge, proof of this is that theories and concepts continue to be used. of the philosophies of occlusion in patient rehabilitation, we follow myths and sophisms that have not been demonstrated, in this review, we demonstrate the great advances in the concepts of occlusion and we know all dentists to break the paradigms of the old occlusion without scientific evidence (AU)

Fuerza de ruptura y adaptación marginal de carillas oclusales confeccionadas con CAD/CAM composite, cerámica híbrida y feldespática fijadas con distintos medios cementantes / Breaking strength and marginal adaptation of occlusal veneers made with CAD / CAM composite, hybrid ceramic and feldspathic fixed with different cementing medium

Resumen Objetivos: a) Comparar la fuerza de ruptura (FR), adaptación marginal externa (AME) y angulación intracuspídea (AI) entre carillas oclusales confeccionadas con composite, cerámica híbrida y feldespática obtenidas con sistemas CADCAM fijadas con distintos medios cementantes y b) evaluar si el medio cementante, la AME y la AI influyen en la FR. Materiales y métodos: 50 premolares conformaron 6 grupos de acuerdo a la combinación de los materiales Cp, omposite Paradigm MZ100 (P), Cerámica híbrida VitaEnamic (VE), Cerámica feldespática Vitablocks Mark II (F) con los cementos Variolink N curado dual (VN) o resina compuesta Z100 calentada (RC): Grupo 1 (n=10) P-VN, Grupo 2 (n=10) P-RC, Grupo 3 (n=10) VE-RC, Grupo 4 (n=10) VE-VN, Grupo 5 (n=5) F-VN, Grupo 6 (n=5) F-RC. Los dientes preparados y acondicionados recibieron carillas confeccionadas utilizando el Sistema Cerec 3. Luego, fueron sometidas a fuerzas compresivas en una máquina de ensayos universal, aplicando una carga con una velocidad de desplazamiento igual a 0,5 mm/ minuto hasta el cese por fractura catastrófica. Previo a realizar los ensayos se midió la AME en sus cuatro caras y la AI. Resultados: Se obtuvieron valores de mayor FR para los Grupos 1 y 2, que se diferenciaron significativamente de los otros 4 grupos (p<0,05). El medio cementante no influyó sobre la FR (p>0,05). Hubo diferencias con relación a los materiales y la AME favoreciendo al Grupo 1 (p<0,05). Conclusiones: Las carillas oclusales confeccionadas en composite con sistemas CAD-CAM (Paradigm MZ100) necesitaron mayor fuerza para provocar su ruptura y registraron menores desadaptaciones.

Abstract Aims: a)To compare the breaking strength (BS), external marginal adaptation (EMA) and intracuspid angulation (ID) between occlusal veneers made with composite, hybrid ceramic and feldspathic obtained with CAD-CAM systems fixed with different cementing medium and b) to evaluate the effect that the cement, the EMA and ID have on the BS. Materials and methods: 50 premolars formed 6 groups according to the combination of the Composite Paradigm MZ100 (P), VitaEnamic hybrid ceramic (VE), Vitablocks Mark II feldspathic ceramic (F) with the dual-cured Variolink N (VN) or Z100 Heated Composite Resin (RC): Group 1 (n10) P-VN, Group 2 (n10) P-RC, Group 3 (n10) VERC, Group 4 (n10) VE-VN, Group 5 (n5) F-VN, Group 6 (n5) F-RC. The teeth received a preparation and were conditioned, subsequently, they received occlusal veneers using the Cerec 3 System. They were then subjected to compressive forces in a Testing Machine, applying a load with a speed of movement equal to 0.5 mm/ minute until it stopped due to catastrophic fracture. Before carrying out the tests, the EAM was registered in four faces and the ID was measured. Results: Higher BS were obtained for Groups 1 and 2, which differed significantly from Groups 3,4,5 and 6 (p<0.05). The cementing medium did not influence the BS (p>0.05). There were differences in relation to the materials and the EMA favoring Group 1 (p<0.05). Conclusions: The occlusal veneers made in composite with CAD-CAM systems (Paradigm MZ100) required greater force to cause their rupture and registered less misadaptations.

Comportamiento de la maloclusión funcional e interferencias oclusales en niños con dentición mixta

Introducción: las interferencias oclusales no controladas precozmente pueden producir desviación de la mandíbula en sentido anteroposterior o transversal. El manejo de las mordidas cruzadas se debe iniciar en el momento del diagnóstico, preferiblemente en edades tempranas, con el fin de tratarlas en el nivel primario de prevención. Objetivo: determinar el comportamiento de la maloclusión funcional causada por interferencias oclusales en niños con dentición mixta de la Escuela Primaria Mártires del Corynthia, entre octubre de 2019 y junio de 2021. Materiales y métodos: se realizó un estudio observacional descriptivo de corte transversal en la Escuela Primaria Mártires del Corynthia, del Área de Salud José Jacinto Milanés, del municipio de Matanzas, entre octubre de 2019 y junio de 2021. El universo estuvo conformado por 66 niños. Se utilizó una planilla de recolección de datos y se solicitó el consentimiento informado a los tutores de los niños. Resultados: las edades donde los niños presentaron mayor afectación fueron de 6 a 7 años y de 8 a 9 años, ambos rangos con un 10,6 %. El 27,3 % presentó interferencias oclusales y mordida cruzada posterior unilateral. El 48,5 % fue del sexo femenino y el 30,3 % tenían edades de 6 a 7 años. El 71,2 % eran simétricos y presentaron mordida cruzada posterior unilateral. Los simétricos y con línea media coincidente representaron un 36,4 %. Conclusiones: la maloclusión funcional más frecuente en niños con dentición mixta fue la mordida cruzada posterior unilateral, que se relacionó de manera directa con las interferencias oclusales. Las asimetrías faciales y la línea media desviada estuvieron asociadas a dicha maloclusión.

Introduction: early uncontrolled occlusal interferences can produce anterior-posterior jaw deflection. Management of cross-bites should be initiated at the time of diagnosis, preferably at early ages, in order to treat them at the primary level of prevention. Objective: to determine the behavior of functional malocclusion caused by occlusal interferences in children with mixed dentition from the Martires del Corynthia primary school between October 2019 and June 2021. Materials and methods: a cross-sectional, observational, descriptive study was carried out at the Martires del Corynthia Primary School, of the Jose Jacinto Milanes Health Area, Matanzas municipality, between October 2019 and June 2021. The universe consisted of 66 children. A data collection form was used and informed consent was requested from the children's guardians. Results: the ages where the children presented more affectation were from 6 to 7 years and from 8 to 9 years, both ranges with 10.6%. 27.3% presented occlusal interferences and posterior unilateral cross-bite. 48.5% were female and 30.3% were 6 to 7 years old. 71.2% were symmetrical and presented unilateral posterior cross-bite. Symmetric patients and with a coincident midline represented 36.4%. Conclusions: the most frequent functional malocclusion in children with mixed dentition was the unilateral posterior cross-bite, which was related to occlusal interferences in a direct way. Facial asymmetries and a deviated midline were associated with the before mentioned malocclusion.

A Study of Post Insertion Problems in Removable Partial Dentures in Kashmiri Population – A Survey Based Research

The aim of this study is to collect data of various post insertion problems in removable partial dentures which were examined in the department of prosthodontics in government dental college srinagar. Around 200 patients were included in the study . The various problems that could be found in removable partial dentures include pain, discomfort, inflammatory conditions, problems in speech, loose dentures, occlusal problems, difficulty in deglutition, residual ridge resorption and altered taste perception.

Comparison between Simple Planas Indirect Tracks and occlusal splints for treatment of temporomandibular disorder-related headache: a randomized controlled clinical trial / Comparação entre Pistas Indiretas Planas Simples e placas miorrelaxantes para tratamento de dor de cabeça relacionada à disfunção temporomandibular: ensaio clínico randomizado

ABSTRACT BACKGROUND AND OBJECTIVES: Temporomandibular disorder-related headache (TMDH) is a very common clinical condition which manifests as pain around the temples. The treatment recommended in dentistry is occlusal splint. However, there is a device generally used in functional jaw orthopedics, called simple Planas indirect tracks (SPIT), which has been shown to be efficient in managing these headaches. This clinical trial aimed to compare SPIT and occlusal splints in the treatment of TMDH patients. METHODS: This randomized clinical trial included thirty-seven women who had TMDH for more than one year into three groups: GPIT treated with SPIT, GSPLINT treated with a Michigan splint, and a control group (CG) submitted to no treatment. The randomization was paired, that is, each new individual was assigned to a group sequentially. The number of headache days per month, average pain intensity, pain response to masseter and temporalis palpation, and days of pain drug use were collected and analyzed. The follow-up lasted for 3 months. RESULTS: Thirty-seven patients were included but 4 dropped out during treatment and 33 underwent intervention. Patients in GPIT exhibited superior results compared to GSPLINT and CG, with significant differences between groups for almost all variables. In GPIT, the number of headache days was reduced by 87.43%, pain intensity by 66.67%, and days of drug use by 88.42%, with significant improvement in all parameters compared to CG. In GSPLINT, the number of headache days decreased by 44.46% and days of drug use by 36.63%, while pain intensity increased by 46.67%; however, there was no significant difference in any of the parameters compared to CG. CONCLUSION: SPIT may be a good treatment option for patients with TMDH since these appliances have shown much more consistent results than occlusal splints. Further studies and with more individuals will be needed to confirm these findings.

RESUMO JUSTIFICATIVA E OBJETIVOS: A cefaleia secundária à disfunção temporomandibular (CDTM), é uma condição clínica muito comum, com dores nas têmporas. O tratamento padrão na odontologia são as placas miorrelaxantes, entretanto um aparelho da ortopedia funcional dos maxilares, chamado de Pistas Indiretas Planas Simples (PIPS), tem se demonstrado eficiente no controle dessas cefaleias. Este estudo clínico visou comparar as PIPS com as placas miorrelaxantes, no quadro álgico de CDTM. MÉTODOS: Este ensaio clínico randomizado incluiu 37 mulheres portadoras de CDTM há mais de um ano, que foram distribuídas aleatoriamente em três grupos: o GPIPS, no qual as pacientes foram tratadas com PIPS, o GPLACA, com uso de placas miorrelaxantes de Michigan e o grupo controle (GC), sem qualquer tratamento. A aleatorização foi pareada, sendo que cada participante era consecutivamente alocada em um grupo diferente. Foram coletados e analisados dias de cefaleia por mês, intensidade de dores, resposta álgica à palpação de masseter e temporal, bem como os dias de uso de fármacos. O acompanhamento foi de três meses. RESULTADOS: Das 37 pacientes iniciais, 4 desistiram do tratamento e apenas 33 foram submetidos a alguma intervenção. As pacientes do GPIPS apresentaram resultados muito superiores às do GPLACA e do GC, com diferenças significativas entre os grupos em quase todas as variáveis. No GPIPS, os dias de dor diminuíram 87,43%, a intensidade 66,67% e os dias de uso de fármacos analgésicos 88,42%, sendo estatisticamente significante a melhora em todos os parâmetros em relação ao GC. Já no GPLACA, os dias de dor diminuíram 44,46% e os dias de uso de fármacos 36,63%, mas a intensidade da dor aumentou 46,67%, porém sem diferença estatisticamente significante em nenhum parâmetro quando comparado ao GC. CONCLUSÃO: O uso do PIPS pode ser uma boa escolha de tratamento da CDTM, tendo apresentado resultados mais consistentes do que as placas miorrelaxantes. Mais estudos e com mais participantes são necessários para confirmar estes achados.

Evaluation of the occlusal contact area of molar dental implants comparing two different thicknesses (16 µm and 200 µm) of articulating occlusal papers and forces (200 and 250 N): a pivot in vitro study

Introduction: The goal of this pilot study was to evaluate the differences between checking occlusion on implants crowns using 16 or 200 µm thickness of articulating occlusal paper, and to compare the stained occlusal area between the groups after bite forces of 200 and 250 N. Methods: It was included 10 casts of articulated-type IV gypsum, 10 NiCr crowns, articulating occlusal papers (16 µm and 200 µm thick), and a compression test machine. Compressive forces (200 and 250 N.mm) were applied on models, to check the occlusal contact area of fixed and cemented crowns. The contact areas on the crowns were measured through images obtained by the scanning electron microscope. Statistical tests were performed considering the significant level of 5% (p≤0.05). Results: The stains found using 200 µm of articulating paper were higher than those with 16 µm, independent of the force applied. However, the stains obtained in lower teeth with different strengths (200 and 250N) marked with 16 µm articulating paper were not possible to score. The articulating paper variable had significant statistical results (p=0.002), while the variables force (p=0.443) and articulating paper-force interaction (p=0.607) were not significant. The mean area found in staining using the 200 µm and 16 µm papers was, respectively, 8.3380 mm2 and 3.4759 mm2. Conclusion: It was possible to confirm that 200 µm of articulating occlusal paper showed better and significant results to stain the occlusal area, permitting a more accurate adjustment independent of the force applied.

The removal of three kinds of occlusal veneers by Er: Yag laser / 华西口腔医学杂志

OBJECTIVES@#This study aimed to remove occlusal veneers of varied thicknesses and compositions by Er:Yag laser in vitro and analyze the interfacial microstructure between veneers and tooth that irradiated by laser, by which experimental evidence could be provided to support the non-invasive removal of occlusal veneerby laser.@*METHODS@#Fresh mandibular premolars extracted for orthodontic requirements were collected for tooth preparation. Three kinds of ceramic materials (Vita Suprinity, Vita Mark Ⅱ, and Upcera Hyramic) were selected to fabricate occlusal veneer with different thicknesses (1.0, 1.5, and 2.0 mm). One week later, Er:Yag laser (2.5 W and 3.5 W) was used to irradiate and remove the occlusal veneer and recorded the timespan. After the removal operation, the micro-morphologies of samples were examined by scanning electron microscope.@*RESULTS@#Upcera Hyramic veneer failed to be removed (>20 min); the operation span at 2.5 W, Vita Suprinity (96.0 s±16.0 s) was longer than Vita MarkⅡ(84.5 s±19.5 s) in the 1.0 mm group (P<0.05), and Vita Suprinity (246.5 s±13.5 s) was longer than Vita MarkⅡ(170.0 s±14.0 s) in the 1.5 mm group (P<0.05). At 3.5 W, Vita Suprinity (381.0 s±24.0 s) was longer than Vita MarkⅡ(341.5 s±26.5 s) in the 2.0 mm group.@*CONCLUSIONS@#Increasing laser power could shorten the operation span and facilitate the removal of occlusal veneers with the same thickness and composition. The occlusal veneer was sustained when insufficient laser power was applied. With the same laser power and ceramic thickness, laser penetration could interfere with the integral of the ceramic structure when the laser interacted with the bonding layer. With the same ceramic composition and laser power, the operation span and laser power increased with the thickness of the occlusal veneer. However, the laser was incapable of removing occlusal resin veneer directly.

The efficacy of muscle function training combined with occlusal inducer in the treatment of malocclusion in children with OSA / 临床耳鼻咽喉头颈外科杂志

Objective:This study aims to investigate the clinical effectiveness of muscle function training combined with occlusal inducers in the treatment for children's malocclusion after obstructive sleep apnea（OSA） surgery. Methods:A total of 40 pediatric patients who underwent surgery for OSA at Shanghai Children's Medical Center, affiliated with Shanghai Jiao Tong University School of Medicine, from January 2020 to December 2021 were involved in this study. They were divided into a treatment group（n=20） and a control group（n=20）. The treatment group received muscle function training combined with occlusal inducers, while the control group received muscle function training alone. Cephalometric measurements of hard tissues were compared between the two groups before and 12 months after surgery. Additionally, the OSA-18 questionnaire, which includes 18 items to assess the life quality of children with OSA, was filled out before surgery, 6 months after surgery, and 12 months after surgery by these patients. Results:①The scores of sleep disorders, physical symptoms, emotional status, daytime sleepiness and energy status and the degree of influence on guardians in the two groups were significantly improved at 12 months after operation（P<0.05）. The scores of sleep disorders, physical symptoms, emotional status and the degree of influence on guardians in the treatment group were better than those in the control group（P<0.05）. ②Cephalometric data at 12 months after operation showed that the upper and lower alveolar seat angle（ANB）, Overbite, upper and lower central incisor angle（U1-L1） and Overjet in the treatment group were lower than those in the control group at 12 months after operation, and the difference was statistically significant（P<0.05）. Conclusion:Children with OSA can improve the dentition irregularity by muscle function training combined with occlusal inducer after operation, and the effect is better than that of muscle function training alone.

Imaging study on the relationship between anterior and posterior occlusal planes and temporomandibular osteoarthrosis / 华西口腔医学杂志

OBJECTIVES@#The aim of this study was to compare the anterior and posterior occlusal plane characteristics of patients with different temporomandibular joint osseous statuses.@*METHODS@#A total of 306 patients with initial cone beam CT (CBCT) and cephalograms were included. They were divided into three groups on the basis of their temporomandibular joint osseous status: bilateral normal (BN) group, indeterminate for osteoarthrosis (I) group, and osteoarthrosis (OA) group. The anterior and posterior occlusal planes (AOP and POP) of the different groups were compared. Then, the regression equation was established after adjusting for confounding factors, and a correlation analysis between the occlusion planes and other parameters was performed.@*RESULTS@#SNA, SNB, FMA, SN-MP, Ar-Go, and S-Go were correlated with the occlusal planes. Relative to the BN and I groups, the FH-OP of the OA group increased by 1.67° on the average, FH-POP increased by 1.42° on the average, and FH-AOP increased by 2.05° on the average.@*CONCLUSIONS@#The occlusal planes were steeper in the patients with temporomandibular osteoarthrosis than in the patients without it, and the mandible rotated downward and backward. The height of the mandibular ramus, the mandibular body length, and the posterior face height were small. In clinical practice, attention should be given to the potential risk of temporomandibular joint osteoarthrosis in such patients. In addition, SNB, FMA, SN-MP, Ar-Go, S-Go, and occlusal planes had moderate correlations.

A comparative study based on the mandibular movement track and the movement parameters of the virtual articulator in simulating occlusal adjustment / 华西口腔医学杂志

OBJECTIVES@#This study aimed to compare the effects of virtual adjustment on occlusal interferences in mandibular posterior single crown and three-unit bridge restorations by using the mandibular movement track and the movement parameters of a virtual articulator.@*METHODS@#Twenty-two participants were recruited. Digital casts of the maxillary and mandibular arches were obtained using an intraoral scanner, and the jaw registration system was used to record the data of the mandibular movement track and the movement parameters of the articulator. Four kinds of restorations with 0.3 mm occlusal interferences were designed with dental design software. In particular, single crowns were designed for teeth 44 and 46, whereas three-unit bridges were designed for teeth 44-46 and 45-47, and the corresponding natural teeth were virtually extracted. Virtual adjustment of the restorations was performed using two dynamic occlusal recordings, namely, the mandibular movement track and the movement parameters of the virtual articulator. A reverse-engineering software was used to measure the root-mean-square of the three-dimensional deviation of the occlusal surfaces between natural teeth and the adjusted restorations. The differences between the two methods of virtual-occlusion adjustment were compared and analyzed.@*RESULTS@#For the same group of restorations, the three-dimensional deviation of the mandibular movement track group were lower than those of the virtual articulator group, and the differences were statistically significant (P<0.05). For the four groups of restorations adjusted by the same method, the three-dimensional deviation of the 46-tooth single crown was the largest and the smallest three-dimensional deviation was that of the 44-tooth single crown. Statistical differences existed between the 44-tooth single crown and the other groups (P<0.05).@*CONCLUSIONS@#For the occlusal design of posterior single crown and three-unit bridge, the mandibular movement track could be a more effective approach to virtual occlusal adjustment than the movement parameters of the virtual articulator.

Implications of occlusal plane in diagnosis and treatment of malocclusion / 浙江大学学报·医学版

Occlusal plane (OP) is one of the essential factors affecting craniofacial morphology and function. The OP not only assists in diagnosing malocclusion but also serves as an important reference for making treatment plans. Patients with different types of malocclusions have different forms of OP. Compared with patients with standard skeletal facial type, the occlusal plane of patients with skeletal class Ⅱ and high angle is steeper, while that of patients with skeletal class Ⅲ and low angle is more even. In orthodontic treatment, adjusting and controlling the OP can promote the normal growth and development of the mandible in most patients with malocclusion during the early stage of growth, while causing favorable rotation of the mandible in some adults with mild-to-moderate malocclusion. For moderate-to-severe malocclusion, the OP rotation by orthodontic-orthognathic treatment can achieve better long-term stability. This article reviews the evolution of the definition of OP and its implications for diagnosing and the guiding treatment of malocclusion.

The importance of properly distributing the occlusal load for the correct biomechanics of implant-supported fixed partial dentures: stress analysis in implants, prosthetic components and infrastructures / A importância da distribuição da carga oclusal de forma adequada para a correta biomecânica de prótese parcial fixa implantosuportada: análise das tensões em implantes, componentes protéticos e infraestruturas

ABSTRACT Objective: The present study analyzed the biomechanical behavior of the generated stress on the external surface of the rehabilitation elements (implants, components and infrastructures) according to different occlusion patterns on a fixed partial denture on osseointegrated implants. Method: The experimental groups varied according to the location of the occlusal load applied to the Fixed partial denture, with a total occlusal load of 750N in all groups, opting for greater loads on the occlusal table of the molar in relation to the premolar. This evaluation was performed by the finite element method with simulations by the AnsysWorkbench 16.0 Software program. Results: The results analyzed for implants and their components showed that the more posterior the occlusal loading, the greater the stress developed (group 4), always in the connection area between the prosthetic component and the implant, as this location can induce greater screw loosening. The results analyzed for the infrastructures showed that the most distributed occlusal loading possible (group 1) is the best situation for generating less stress. However, even in group 3 which obtained the highest stresses in the critical area of the prosthetic connection, the zirconia flexural strength values generated were not worrisome. Conclusion: It can be concluded that the occlusal adjustment of Fixed partial dentures are preponderant and decisive factors for correct biomechanics and preservation of the system in the long term in order to avoid possible damage and/or failures, and exert significant and notorious differences in the behavior of all structures studied herein.

RESUMO Objetivo: O presente estudo analisou o comportamento biomecânico do estresse gerado na superfície externa dos elementos reabilitadores (implantes, componentes e infraestruturas) de acordo com diferentes padrões de oclusão em uma prótese parcial fixa sobre implantes osseointegrados. Métodos: Os grupos experimentais variaram de acordo com a localização da carga oclusal aplicada na Prótese Parcial Fixa, com carga oclusal total de 750N em todos os grupos, optando por cargas maiores na mesa oclusal do molar em relação ao pré-molar. Esta avaliação foi realizada pelo método dos elementos finitos com simulações pelo programa AnsysWorkbench 16.0 Software. Resultados: Os resultados analisados para os implantes e seus componentes mostraram que quanto mais posterior a carga oclusal, maior a tensão desenvolvida (grupo 4), sempre na área de conexão entre o componente protético e o implante, pois este local pode induzir maior soltura do parafuso. Os resultados analisados para as infraestruturas mostraram que a carga oclusal mais distribuída possível (grupo 1) é a melhor situação para gerar menos estresse. No entanto, mesmo no grupo 3 que obteve as maiores tensões na área crítica da conexão protética, os valores de resistência à flexão da zircônia gerados não foram preocupantes. Conclusões: Pode-se concluir que o ajuste oclusal das Próteses Parciais Fixas são fatores preponderantes e decisivos para correta biomecânica e preservação do sistema a longo prazo a fim de evitar possíveis danos e/ou falhas, e exercem diferenças significativas e notórias no comportamento de todas as estruturas aqui estudadas.

Evaluation of the mechanical properties of different materials for manufacturing occlusal splints

Abstract This study aimed to compare the mechanical properties of various occlusal plate materials by analyzing surface roughness, Knoop microhardness, flexural strength, and modulus of elasticity. Fifty samples were prepared and classified as SC (self-curing acrylic resin), WB (heat-cured acrylic resin), ME (acrylic resin polymerized by microwave energy), P (resin print), and M (polymethylmethacrylate polymer block for computer-aided design/computer-aided manufacturing). The data were analyzed using a one-way analysis of variance and Tukey's honestly significant difference test. Surface roughness was the same in all groups. The surface hardness of group M was statistically superior. The samples from groups P and M had higher flexural strength than other samples. The modulus of elasticity of group SC was statistically lower than that of other groups. The mechanical properties of the materials used to make the occlusal plates differed, and group M achieved the best results in all analyses. Therefore, clinicians must consider the material used to manufacture long-lasting and efficient occlusal splints.

Resistência flexural de uma resina para impressão 3D comparada a resinas acrílicas convencionais empregadas para confecção de placas estabilizadoras de mordida / Flexural resistance of 3D printing resin compared to conventional acrylic resins employed to build occlusal bite splints

Introduction: with the technological advance in dentistry, light-polymerized three-dimensional (3D) printing resins had become an alternative for the manufacture of occlusal splint splints. Objective: the present study aimed to analyze the flexural strength of a resin for 3D printing compared to conventional acrylic resins (chemically activated and thermally activated), under the influence of thermocycling. Material and method: 60 specimens were made, which were distributed in six experimental groups (n = 10), according to the resin employed (chemically activated acrylic resin, thermally activated acrylic resin and 3D printing resin) and the treatment received (control and thermocycling). The specimens were submitted to flexural strength by the three-point flexural test. Result: data analysis showed that the material factor (<0.0001) and the thermocycling factor (p = 0.0096) influenced flexural strength, however, the interaction between the two factors did not (p = 0.9728). Conclusion: it was concluded that 3D printing resins presented the lowest flexural resistance to acrylic resins, especially when submitted to thermocycling.

Introdução: com o avanço tecnológico dentro da odontologia, as resinas fotopolimerizáveis para impressão tridimensional (3D) se tornaram uma alternativa para a fabricação de dispositivos interoclusais. Objetivo: o presente trabalho teve como objetivo analisar a resistência flexural de uma resina para impressão tridimensional comparada com resinas acrílicas convencionais (quimicamente ativada e termicamente ativada), sob a influência da termociclagem. Material e método: foram confeccionados 60 corpos de prova, que foram distribuídos aleatoriamente em seis grupos experimentais (n=10), de acordo com a resina utilizada (resina acrílica ativada quimicamente, resina acrílica ativada termicamente e resina para impressão 3D) e com o tratamento recebido (controle e termociclagem). Os corpos de prova foram submetidos ao ensaio de flexão de três pontos para determinação da resistência flexural. Resultado: a análise dos dados demonstrou que o fator material (<0.0001) e o fator termociclagem (p=0.0096) influenciaram a resistência flexural, entretanto, a interação entre os dois fatores não (p=0.9728). Conclusão: deste modo podemos concluir que a resina para impressão 3D apresentou desempenho inferior às resinas acrílicas, especialmente quando submetida a termociclagem.

Effect of laboratory and chairside polishing methods on the surface topography of occlusal splint materials manufactured using conventional, subtractive and additive digital technologies / Efeito de métodos de polimento em laboratório e em consultório na topografia de superfície de materiais de splint oclusal fabricados usando tecnologias digitais convencionais, subtrativas e aditivas

Objetivo: Este estudo avaliou as propriedades de polimento dos materiais de splint oclusal obtidos usando métodos de fabricação subtrativos e aditivos com os procedimentos de polimento laboratorial (LP) e polimento em consultório (CP). Material e Métodos: As amostras (N=180, n=60 para cada grupo) foram fabricadas usando um dos seguintes métodos: método de fabricação subtrativo (SMM) (M-PM Disc, Merz Dental GmbH), método de fabricação aditivo (AMM) (Freeprint Splint 2.0, DETAX GmbH & Co. KG) e o método de fabricação convencional (CMM) (Promolux HC, Merz Dental GmbH). Seguindo os procedimentos de LP e CP, a rugosidade da superfície dos espécimes foi medida usando um perfilômetro de superfície digital. Um espécime representativo foi selecionado de cada grupo, e uma imagem de microscópio eletrônico de varredura (SEM) foi obtida. Resultados: Tanto o método de fabricação quanto os procedimentos de polimento afetaram significativamente os resultados (P<0,01). Os termos de interação também foram significativos (P<0,001). Conclusão: Com ambos os métodos de polimento, a rugosidade superficial do grupo AMM foi a maior e a do grupo CMM a menor. Embora o procedimento CP tenha sido mais eficaz do que LP com ambos os métodos, a rugosidade da superfície ficou abaixo do limite de 0,2 µm após ambos os procedimentos de polimento testados (AU)

Objective: This study evaluated the polishing properties of the occlusal splint materials obtained using subtractive and additive manufacturing methods with the laboratory-type polishing (LP) and chairside-type polishing (CP) procedures. Material and Methods: Specimens (N=180, n=60 each group) were manufactured using one of the following methods: subtractive manufacturing method (SMM) (M-PM Disc, Merz Dental GmbH), additive manufacturing method (AMM) (Freeprint Splint 2.0, DETAX GmbH & Co. KG), and the conventional manufacturing method (CMM) (Promolux HC, Merz Dental GmbH). Following LP and CP procedures, surface roughness of the specimens was measured using a digital surface profilometer. One representative specimen was selected from each group, and a scanning electron microscope (SEM) image was made. Results: Both the manufacturing method and the polishing procedures significantly affected the results (P<0.01). Interaction terms were also significant (P<0.001). Conclusion: With both polishing methods, surface roughness of the AMM group was the highest and the CMM group the least. Although the CP procedure was more effective than LP with both methods, surface roughness was below the 0.2 µm threshold after both polishing procedures tested. (AU)

Efectividad de Férulas de Descarga Oclusivas como Tratamiento para la Disfunción Temporomandibular. Revisión Sistemática

El objetivo de este estudio de revisión sistemática consistió en la búsqueda de hallazgos clínicos en estudios de calidad sobre la efectividad de la terapia con férulas de descarga oclusales. Esta investigación bibliográfica se realizó en PubMed, Embase, SciELO, Science Direct, Scopus, Google Scholar y en el Registro Central de Ensayos clínicos Cochrane; delimitando la búsqueda desde el 1 de enero de 2011 al 1 de junio de 2022. Se incluyeron un total de 21 artículos, todos relacionados con la disfunción de la articulación temporomandibular y la eficacia de las férulas de descarga oclusales como tratamiento. Las férulas de descarga oclusales reducen eficazmente los síntomas dolorosos en pacientes con trastornos temporomandibulares, tanto en patologías musculares como articulares, aunque con mayor eficacia en casos de disfunción muscular, ya que se han observado desplazamientos recurrentes de disco en patologías articulares.

The objective of this systematic review study was to search for clinical findings in quality studies on the effectiveness of occlusal splint therapy. This literature search was conducted in PubMed, Embase, SciELO, Science Direct, Scopus, Google Scholar, and the Cochrane Central Register of Clinical Trials; delimiting the search from January 1, 2011 to June 1, 2022. A total of 21 articles were included, all related to temporomandibular joint dysfunction and the efficacy of occlusal splints as a treatment. Occlusal splints effectively reduce painful symptoms in patients with temporomandibular disorders, both in muscular and joint pathologies, although more effectively in cases of muscular dysfunction, since recurrent disc displacements have been observed in joint pathologies.

Stress distribution in occlusal veneers with different finish lines when applying vertical and tangential forces / Distribución de estrés en carillas con diferentes líneas de terminación aplicando fuerzas verticales y tangenciales

Abstract To evaluate stress distribution when applying vertical and tangential forces to 1mm thick occlusal veneers with different finish lines preparations, using the finite element method. One extracted third molar was prepared for occlusal veneers, firstly without any bevel. It was scanned in order to design two groups of lithium disilicate (G1A, G2A) and composite resin (G1B, G2B) occlusal veneers. Then, the third molar preparation was modified, beveling the finish line and it was subsequently scanned again to design the occlusal veneer groups with bevel (LD: G3A, G4A and CR: G3B, G4B). The four groups were subjected to different forces (400 N vertical and 900 N tangential). At 400 N, the non-beveled veneers showed slightly higher Von Mises stress values (G1A: 783 MPa and G1B 736.5 MPa) than the beveled veneers (G3A: 685.7 MPa and G3B: 675.8 MPa). However, when 900 N tangential forces were applied, the beveled occlusal veneers showed higher Von Mises stress values (G4A: 4297 MPa and G4B: 4133 MPa) than the non-beveled occlusal veneers (G2A: 2581.1 MPa and G2B: 3519.1 MPa). Furthermore, it was observed that the tissue under the occlusal veneers with bevel showed higher Von Mises stress values than the models without any bevel. Beveled and non-beveled occlusal veneers of lithium disilicate and composite resin presented similar stress distribution values when vertical forces of 400 N were applied; whereas with tangential forces of 900 N applied near to the finish line, the beveled groups presented notably higher stress values than the non-beveled groups. However, both finish line preparations presented adequate values for possible clinical performance.

Resumen Evaluar la distribución de estrés al aplicar fuerzas verticales y tangenciales en carillas oclusales de 1mm de espesor con diferentes líneas de terminación marginal por el método de elementos finitos. Se preparó un tercer molar extraído para carilla oclusal, primero sin bisel. Se escaneó para diseñar dos grupos de carillas oclusales de disilicato de litio (G1A, G2A) y resina compuesta (G1B, G2B). Después, esta preparación molar fue modificada, biselando la línea de terminación y escaneándola nuevamente para diseñar los grupos de carillas oclusales con bisel (DL: G3A, G4A and RC: G3B, G4B). Los 4 grupos fueron sometidos a fuerzas diferentes (400 N vertical y 900 N tangencial). Con 400 N, las carillas sin bisel presentaron ligera mayor tensión de Von Mises (G1A: 783 MPa y G1B 736.5 MPa) que las carillas con bisel (G3A: 685.7 MPa y G3B: 675.8 MPa). De distinta forma, al aplicar fuerzas tangenciales de 900 N, las carillas oclusales con bisel presentaron mayor tensión de Von Mises (G4A: 4297 MPa y G4B: 4133 MPa) que las carillas oclusales sin bisel (G2A: 2581.1 MPa y G2B: 3519.1 MPa). Además, se observó que los tejidos subyacentes a las carillas oclusales con bisel, presentaron mayor tensión de Von Mises, frente a los modelos sin bisel. Las carillas oclusales con y sin bisel de disilicato de litio y resina compuesta presentaron una distribución de estrés similar con fuerzas verticales de 400 N, por otro lado, con fuerzas tangenciales de 900 N, los grupos con bisel presentaron notablemente mayor tensión que los grupos sin bisel. Sin embargo, ambos diseños de terminación marginal presentaron valores adecuados para un posible desempeño clínico.